磁盘空间不够用？centos7如何给分区扩容
一、前言
今天发现，服务器的/home 目录的硬盘空间被挤满了，原因是mysql的大量数据占据了大多的内存，因此，需要对内存进行重新分区，命令如下：
[superadmin@localhost ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 600G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 199G 0 part
├─centos-root 253:0 0 50G 0 lvm /
├─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
└─centos-home 253:2 0 145.1G 0 lvm /home
sr0 11:0 1 4.5G 0 rom
[superadmin@localhost home]# du -h --max-depth=1 |grep 'G' |sort
118G ./mysql8
145G .
25G ./nacos
在磁盘中，我们看到sda分配了600G的内存，但只分了两个sda1 和sda2，还剩余400G的内存未分配，造成了极大的浪费，因此需要先新建分区。
二、新建分区
新建后，需要刷新分区后才能看到新的分区sda3，如果还是不行就重启试试。
给新的分区300G 内存，剩余100G备用。
[superadmin@localhost home]# fdisk /dev/sda
欢迎使用 fdisk (util-linux 2.23.2)。
更改将停留在内存中，直到您决定将更改写入磁盘。
使用写入命令前请三思。
命令(输入 m 获取帮助)：n
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p):
Using default response p
分区号 (3,4，默认 3)：3
起始 扇区 (419430400-1258291199，默认为 419430400)：
将使用默认值 419430400
Last 扇区, +扇区 or +size{K,M,G} (419430400-1258291199，默认为 1258291199)：1048575999
分区 3 已设置为 Linux 类型，大小设为 300 GiB
命令(输入 m 获取帮助)：w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: 设备或资源忙.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
正在同步磁盘。
[superadmin@localhost home]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 600G 0 disk
├─sda1 8:1 0 1G 0 part /boot
└─sda2 8:2 0 199G 0 part
├─centos-root 253:0 0 50G 0 lvm /
├─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
└─centos-home 253:2 0 145.1G 0 lvm /home
sr0 11:0 1 4.5G 0 rom
[superadmin@localhost home]# partprobe /dev/sda
[superadmin@localhost home]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 600G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 199G 0 part
│ ├─centos-root 253:0 0 50G 0 lvm /
│ ├─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
│ └─centos-home 253:2 0 145.1G 0 lvm /home
└─sda3 8:3 0 300G 0 part
sr0 11:0 1 4.5G 0 rom
三、分配内存
1、将新分区的sda3 分区创建为物理卷
[superadmin@localhost home]# pvcreate /dev/sda3
Physical volume "/dev/sda3" successfully created.
2、将创建好的物理卷扩展到/home所在卷组
[superadmin@localhost home]# vgdisplay -v
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 1
Act PV 1
VG Size <199.00 GiB
PE Size 4.00 MiB
Total PE 50943
Alloc PE / Size 50942 / 198.99 GiB
Free PE / Size 1 / 4.00 MiB
VG UUID ditVGC-NFOL-cOTM-fW4Z-Btv4-yKLW-T1riU6
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID DHEcu3-r7yQ-dcKB-ZvBV-1aZl-gbPT-CFGmf0
LV Write Access read/write
LV Creation host, time localhost, 2020-06-15 23:32:37 +0800
LV Status available
# open 2
LV Size <3.88 GiB
Current LE 992
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/home # 这个是我们目的扩容的目录
LV Name home
VG Name centos # 这个是分区所在卷组名字
LV UUID kv17CJ-xC2V-olZV-5tL0-W1QM-ud5Y-c8PBwO
LV Write Access read/write
LV Creation host, time localhost, 2020-06-15 23:32:37 +0800
LV Status available
# open 1
LV Size <145.12 GiB
Current LE 37150
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Logical volume ---
LV Path /dev/centos/root # 这个是根分区所挂载的逻辑卷路径
LV Name root
VG Name centos # 这个是根分区所在卷组名字
LV UUID bA2a4N-7Alz-xNyU-FcWX-t8eX-Q4E8-ELqf8o
LV Write Access read/write
LV Creation host, time localhost, 2020-06-15 23:32:37 +0800
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Physical volumes ---
PV Name /dev/sda2
PV UUID hpbzq1-xMEL-PeVv-veFD-hrB2-13be-hjzcZr
PV Status allocatable
Total PE / Free PE 50943 / 1
扩展卷组容量：
[superadmin@localhost home]# vgextend centos /dev/sda3
Volume group "centos" successfully extended
3、扩展/home 分区所挂载的逻辑卷路径并使扩容生效
# 将剩余可用容量全部扩展到 /dev/centos/home
[superadmin@localhost home]# lvextend -l +100%FREE /dev/centos/home
Size of logical volume centos/home changed from <145.12 GiB (37150 extents) to <445.12 GiB (113950 extents).
Logical volume centos/home successfully resized.
[superadmin@localhost home]# xfs_growfs /dev/centos/home
meta-data=/dev/mapper/centos-home isize=512 agcount=4, agsize=9510400 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=38041600, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=18575, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 38041600 to 116684800
4、查看扩展后的/home 分区容量
[superadmin@localhost home]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 600G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 199G 0 part
│ ├─centos-root 253:0 0 50G 0 lvm /
│ ├─centos-swap 253:1 0 3.9G 0 lvm [SWAP]
│ └─centos-home 253:2 0 445.1G 0 lvm /home
└─sda3 8:3 0 300G 0 part
└─centos-home 253:2 0 445.1G 0 lvm /home
sr0 11:0 1 4.5G 0 rom
最后，大功告成！